cb350 carb help, warning newbie content

[tommycreeper]

I want to start off by saying this forum is great, I am learning so much already.

I have a 73 cb350 with 722a carbs. I have been having trouble getting them to work properly. At first it was bogging down at low RPM then taking off. I went through and cleaned everything. Now it is harder to start but eventually does. I let it warm up, then I go to ride. When I start going down the road the rpms rev up on their own and the bike remains at the same speed. When I come to a stop I have the clutch engaged and the rpms rev up again. Where should I start, I am at a loss.

 

[Big R]

1:When I start going down the road the rpms rev up on their own and the bike remains at the same speed.

2:When I come to a stop I have the clutch engaged and the rpms rev up again.

1: When your revs go up like that, it means your clutch is slipping. Either your cable needs adjusted, or you have the wrong oil in the motor, or your plates are worn, etc.

2: Most likely you have an air leak around the intake boots. With the motor at idle, spray some wd40 around the rubber - if the idle speed changes, you found your leak.

 

[tommycreeper]

1. This makes sense. When I go the engine revs but I move at a slow speed almost like the clutch is still half engaged. Do I start with adjusting the cable? What is the proper way to do that? Also, what oil should I use? Thanks for the info!

 

[Big R]

The cable adjustments are in the service manual - if you don't have one, get one! You'll need it. Any cycle specific oil will work, just get the grade specified in the manual.

 

[tommycreeper]

Rich, thank you for all the advice. I started messing with it more today. I started it and let it idle for a while and while still in neutral I revved it up and the RPMs stayed high, around 5000. Then the right carb quit working. I had this problem with it not working before. Someone suggested the needle valve needed to be clean so I did so. After doing this is when I started having the high RPM problem. Should the needle valve be replaced or am I looking at a different problem?

 

[DrJ]

Carbs are only half the ignition equation. What about your electrics such as coils, plugs and timing?

 

[tommycreeper]

I noticed that adjusting the pilot screw on one of the carbs doesn't make a difference. That seems like a problem. How do I fix that?

 

[Big R]

Pull the screw out all the way (be careful of the spring) and make sure the tip of it isn't cracked apart. If it is OK, then the screw should be doing something.......

 

[tommycreeper]

Jesus!!! Ok well, I did that and the screw looked fine. I put it back in and it started working properly. So I went and adjusted everything on the carb. I got the idle perfect(about 1200). I took it for a spin and it was running GREAT even better than when I bought it. After about 15 minutes of riding it lost everything, it acted like it was running out of gas, then it died. I went to start it wouldn't start. I turned the choke on and it started right up, then it wanted to die when I turned the choke off. So the whole way home I had to keep adjusting the choke back and forth to keep it running. When I got home I let it sit for a half hour and then it started running normal again. Now what?

BTW thanks for all the help! I hope I'm not annoying you.

 

[teazer]

Open the gas cap and clean out the tiny breather hole that lets air in as the gas comes out.

 

[tommycreeper]

It actually doesn't have a seal on it. I have one ordered.

 

[Big R]

You mean the rubber gasket on the gas cap? Pretty important if so.......

What Teazer means is it sounds like your carbs are starving for fuel. Usually it's the gas cap breather hole, but it can be a clogged fuel filter (stock is inside the petcock), a pinched fuel line, clogged carb breather vents, etc.